MEAN Angular Components and Services 3

Question 1

What are Angular Reactive Forms and how do they differ from Template-Driven Forms?

Accepted Answer

Reactive Forms are defined in the component class and provide synchronous access to the form model; Template-Driven Forms are defined in the template

Answer

Reactive Forms use FormControl, FormGroup, and FormBuilder in the component class, giving explicit control over validation and state; Template-Driven Forms rely on ngModel directives.

Question 2

What does the `trackBy` function do when used with `*ngFor`?

Accepted Answer

Tells Angular how to track items uniquely to minimize DOM re-rendering when the list changes

Answer

trackBy provides a unique identifier for each list item so Angular can reuse existing DOM nodes instead of destroying and recreating them when data changes.

Question 3

What is the role of `NgModule` in an Angular application?

Accepted Answer

Groups related components, directives, pipes, and services into a cohesive block of functionality

Answer

NgModule uses the @NgModule decorator to declare components/directives/pipes it owns, import other modules it needs, and export what it makes available to others.

Question 4

How does Angular's dependency injection hierarchy work?

Accepted Answer

Injectors are hierarchical; a child injector inherits from its parent but can override providers locally

Answer

Angular creates a tree of injectors mirroring the component tree; a component first looks for a provider in its own injector, then walks up to parent injectors.

Question 5

What is the Angular CLI command to generate a new service?

Accepted Answer

ng generate service service-name

Answer

ng generate service (or ng g s) creates a new service file with the @Injectable() decorator and adds the spec file for testing.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Angular Components and Services 3